Narrow stripe membrane BH-DFB lasers with surface corrugation for stable single-mode operation

A stable single-mode operation of membrane BH-DFB lasers was demonstrated under RT-CW operation by adopting a surface corrugation structure in order to maintain high index-coupling coefficient even for very narrow stripe width condition. It was estimated to be around 3000 cm^-1 for 0.6 mum stripe width from its stop-band width of 68 nm. A threshold pump power as low as 0.69 mW (lambda_pump = 980 nm) was achieved for the stripe width of 1.0 mum and the cavity length of 120 mum. By assuming an absorption coefficient of the pump beam of GaInAsP optical confinement layers and the active region to be 10000 cm^-1, the corresponding threshold current was estimated to be 17 muA